#!/bin/sh

set -euo pipefail

bold="\033[1m"
reset="\033[0m"

unreleased_for() {
    DIR=$1

    CARGO_MANIFEST=$DIR/Cargo.toml
    CHANGELOG_FILE=$DIR/CHANGES.md

    # get current version
    PACKAGE_NAME="$(sed -nE 's/^name ?= ?"([^"]+)"$/\1/ p' "$CARGO_MANIFEST" | head -n 1)"
    CURRENT_VERSION="$(sed -nE 's/^version ?= ?"([^"]+)"$/\1/ p' "$CARGO_MANIFEST")"

    CHANGE_CHUNK_FILE="$(mktemp)"

    # get changelog chunk and save to temp file
    cat "$CHANGELOG_FILE" |
        # skip up to unreleased heading
        sed '1,/Unreleased/ d' |
        # take up to previous version heading
        sed "/$CURRENT_VERSION/ q" |
        # drop last line
        sed '$d' \
            >"$CHANGE_CHUNK_FILE"

    # if word count of changelog chunk is 0 then exit
    if [ "$(wc -w "$CHANGE_CHUNK_FILE" | awk '{ print $1 }')" = "0" ]; then
        return 0;
    fi

    echo "${bold}# ${PACKAGE_NAME}${reset} since ${bold}v$CURRENT_VERSION${reset}"
    cat "$CHANGE_CHUNK_FILE"
}

for f in $(fd --absolute-path CHANGES.md); do
    unreleased_for $(dirname $f)
done